Protective coating for carbon bodies.



life.

HERMANN VIERTEL, OF LICI-ITENBERG, NEAR BERLIN, AND GEORG EGLY, 0F TREP- TOW, NEAR BERLIN, GERMANY, ASSIGNORS TO GEBRUEDER SIEMENS & 00., OF LICHTENBERG,' NEAR BERLIN, GERMANY. I

FFTQ.

PROTECTIVE COATING FOR CARBON BODIES.

No Drawing.

To all whom it may concern:

Be it known that we, HERMANN V IERTEL and Gnono EGLY, subjects of the German Emperor, and residing, respectively, at Lichtenberg and Treptow, near Berlin, Germany, have invented certain new and useful Improvements in Protective Coatings. for Carbon Bodies, of which the following is a specification.

According to this invention bodies consisting of a carbon mass are provided with a coating which is intimately connected with the. surface of the carbon body and consists of silit. Silit is a mass which has been introduced into the art during recent years, sub stantially consists of silicon carbon and nitrogen and is obtained, for example, according to the process disclosed in the United States Letters Patent No. 866,444. The silit mass has the advantage that it can be united very securely with carbon bodies and, further, it does not crack or split off when sub jected to considerable variations of temperature. This property of intimately uniting with the carbon surface and not losing the coherence of its parts among themselves andswith the carbon when subjected to the most various kinds of strains in question enables the special properties of the silit mass to be utilized for the present purpose, namely for obtaining a protective coating for carbon bodies.

The protective action of the layer of silit is above all due to the layer of silit being more resisting, in many respects, than car bon. Above all, silit is hardly attacked at all by the oxygen 'of the air at a high temperature, while carbon burn s' away very rapidly. The coating of silit therefore im-' parts to electrical heaters, for example, which consist of carbon, a very much longer Carbon, 1s also but little suitable for many electrolytic purposes, because it is destroyed and the bath becomes impure.- For this purpose, also, the silit coating renders the carbon considerably more resisting.

It might be thought that carbon might Specification of Letters Patent.

Application filed May 26,

Patented Nov. 22, 1910. 1910. Serial No. 563,520:

I be entirely substituted by silit for the mentioned and other purposes. This would have two very important disadvantages, however, namely, on the one hand silit is very much more expensive than carbon, andon the other hand the conductivity of silit is materially less than that of carbon. body principally consisting of carbon with a coating of silit adhering to its surface the advantage of silit is fullyutilized, but the cost of manufacture is considerably diminished and the sphere of employment of such bodies thereby materially increased. The advantage of the high conductivity of carbon is profited by simultaneously.

to carbon bodies in a simple manner by painting or otherwise applying the' silit while it is still plastic, thus before the heating process described in the Letters Patent and subsequently converting it into its final state by heating in a nitrogenous atmosphere.

\Ve claim:

1. As a new article of manufacture, a carbon body having a protective layer of silit firmly united with the surface thereof.

2. As a new article of manufacture, an electrically conductive carbon body having an electrically conductive protective coating of silit firmly adhering to the surface thereof.

3. An electrode comprising an electrically conductive carbon body having an electrically conductive protective coating of silit firmly adhering to the surface thereof.

4. An'electrode, for wet electrolysis, consisting of a carbon bodv havinga protective coating of silit.

In testimony whereof we have signed our names to this specification in the presence of two witnesses.

HERMANN VIERTEL.

'GEORG EGLY.

\Vitnesses:

WOLDEMAR HAUPT, HENRY HASPER.

Bv cormbinin a- A protective layer of silit can be applied 

